Threads: Concurrency and Parallelism in Computer Systems

This lecture discusses the thread abstraction in computer systems, highlighting its importance for concurrency and parallelism. It explains how a process can have multiple threads that share the same address space and file descriptors, allowing for efficient data sharing. Each thread has its own stack and is independently scheduled by the operating system, enabling concurrent execution. The lecture contrasts single-threaded and multi-threaded address spaces, emphasizing the need for careful management of stack space to prevent overflow. The instructor outlines the benefits of using threads, such as improved responsiveness in applications and the ability to exploit multiple CPUs for parallel execution. The lecture also covers the POSIX thread API, detailing functions like pthread_create and pthread_join for thread management. An illustrative example demonstrates potential issues with shared variables in multi-threaded programs, particularly focusing on race conditions and the impact of uncontrolled scheduling on program correctness. The discussion concludes with insights into the behavior of concurrent threads on modern multi-core systems.